Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 74300 | Metric tons, gross weight | NA |
| 2003 | 116455 | Metric tons, gross weight | 56.74% |
| 2004 | 320200 | Metric tons, gross weight | 174.96% |
| 2005 | 772000 | Metric tons, gross weight | 141.10% |
| 2006 | 966065 | Metric tons, gross weight | 25.14% |
| 2007 | 776681 | Metric tons, gross weight | -19.60% |
| 2008 | 913000 | Metric tons, gross weight | 17.55% |
| 2009 | 416194 | Metric tons, gross weight | -54.41% |
| 2010 | 400000 | Metric tons, gross weight | -3.89% |
| 2011 | 662000 | Metric tons, gross weight | 65.50% |
| 2012 | 660000 | Metric tons, gross weight | -0.30% |
